Ultrasonic Thrombolysis for Pulmonary Embolism in the Cath Lab: First Two Cases at Banner Desert Medical Center

Case #1

Patient one is a 62-year-old male, presenting to the emergency department (ED) via emergency medical services after going to his primary care provider (PCP) with complaints of severe shortness of breath for the past three days. He was at a point where he could not take a few steps without becoming short of breath. He was even short of breath at rest. His PCP felt the patient was either having a myocardial infarction (MI) or had a pulmonary embolism (PE). A spiral computed tomography (CT) was done and revealed a large saddle PE sitting at the pulmonary artery trunk. The patient was started on heparin therapy per protocol. 

The emergency physician consulted a cardiologist trained in ultrasonic pulmonary thrombolysis. The cardiologist ordered an echocardiogram that revealed severe right ventricular enlargement, right ventricular dysfunction, and pulmonary hypertension with a normal left ventricular systolic function. These findings are suggestive of a high-risk pulmonary embolism with severe right ventricular enlargement and right ventricular dysfunction with pulmonary hypertension in the acute care setting. The right ventricular systolic pressure was estimated to be 63mmHg and the right atrial pressure was estimated at 15mmHg.

If not treated with some form of thrombolytic therapy, this patient has a high 30-day mortality. The risks and benefits of utilizing ultrasonic thrombolysis were discussed with the patient and his wife. They elected to proceed. The patient was taken to the cardiac cath lab, identified, and introduced to the staff. He was then prepped and draped in the normal fashion, and a time out was done. Two 7 French (Fr) introducers were inserted into the right femoral vein without incident. A 7 Fr Swan Ganz catheter was floated to the left pulmonary artery (LPA). An 0.18” V wire was inserted through the Swan into the LPA and an over-the-wire exchange was done, introducing an ultrasound accelerated thrombolysis catheter (EKOS Corporation) into the LPA. This process was repeated in the right pulmonary artery (RPA) without incident. Once in place, the exchange wires were removed and the ultrasonic wire (EKOS Corporation) was placed in the ultrasound accelerated thrombolysis catheter. The device was then connected to tPA to run at .5mg/hr, per catheter. Each catheter was also connected to normal saline to run as coolant for the ultrasonic catheters. Catheters were secured in place and the patient was transferred to the intensive care unit (ICU) for continued care. 

The patient’s O2 saturations normalized throughout the night and the oxygen was decreased. By the time the catheters were removed, he was speaking without any shortness of breath and stated he was feeling much better. By day two, the patient was on room air, and transferred to the telemetry unit on heparin and coumadin therapy. The patient verbalized he was feeling “really good.” The echocardiogram done on day two showed no pulmonary hypertension.

Case #2

Two days later, patient number two, a 52-year-old female, rolled into the ED with complaints of chest pain and shortness of breath that had been going on for a couple of days, but had gotten worse that day. She was status post right foot surgery one month prior. Upon completion of a spiral CT, this patient was noted to have an acute pulmonary embolism with significant clot burden. Her first echocardiogram showed evidence of moderate pulmonary hypertension with an estimated right ventricular systolic pressure of 48mmHg. Her right atrial pressure was estimated at 15mmHg. She was tachycardic, hypoxic and dehydrated. She received a fluid bolus in the ED prior to transfer to the cardiac cath lab. 

Upon cardiology consultation and evaluation, she was determined to be an appropriate candidate for intravascular ultrasonic thrombolysis. The cardiac cath lab was notified and the patient underwent the placement of two ultrasonic thrombolytic catheters, one in each pulmonary artery with the same gtts and process as noted above. She was then transferred to the ICU for continuation of care. When the physician came in to remove the ultrasound accelerated thrombolysis catheters, the patient was normotensive, with a normal sinus rhythm in the 80’s. An echocardiogram done two days later showed trace tricuspid regurgitation, with right ventricular pressure estimated at 29mmHg and right atrial pressure estimated at 5mmHg. The patient stated she felt “so much better.” Seventy-two hours later, the patient was put on heparin/coumadin therapy, room air, and according to her, she was just waiting for her INR to come up so she could go home. 

Both patients received echocardiograms after 72 hours of therapy. Patient one still had some clot burden and was continued on heparin therapy. He was reportedly asymptomatic other than having difficulty lying on his left side.    

Discussion

Ultrasound accelerated thrombolysis is not for everyone. Like all medical procedures, this procedure has a list of inclusion and exclusion criteria. To be considered an appropriate candidate, the patient must meet the following inclusion criteria:

• PE symptoms < 14 days;
• Elevated cardiac markers;
• Filling defect by contrast-enhanced chest CT in at least one main or proximal lower lobe pulmonary artery;
• Right ventricular dysfunction confirmed by echocardiography with a right ventricular/left ventricular end diastolic diameter ratio equal to or greater than 1.0; right ventricular enlargement by computed tomography angiography (CTA);
• Age 18 to 80 years.

There are numerous exclusion criteria. Many criteria are common to those used when considering any thrombolytic:

• Age < 18;
• PE symptoms > 14 days;
• Insufficient echocardiographic image quality in the apical or subcostal four-chamber view that prohibits the measurement of the right and left ventricular end-diastolic dimensions;
• Known significant bleeding risk;
• Administration of thrombolytic agents within the previous four days;
• Active bleeding;
• Known bleeding diathesis;
• Known coagulation disorder;
• History of intracranial or intra-spinal bleed;
• Intracranial neoplasm or aneurysm;
• Recent gastrointestinal bleed;
• Recent eye surgery, trauma, CPR, obstetrical delivery, or other invasive procedure;
• Allergy, hypersensitivity to heparin, or contrast;
• Estimated glomerular filtration rate < 50 ml/mn;
• Hemodynamic collapse at presentation;
• Severe hypertension;
• Pregnant or lactating;
• Participating in any investigational drug or device study;
• Life expectancy < 90 days;
• Known right-to-left shunt;
• Right atrial thrombus > 10mm.

While the exclusion criteria are an extensive list, ultrasound accelerated thrombolysis is definitely a life-saving procedure for those that meet the inclusion criteria. The rapid improvement of clinical symptoms is remarkable and reason enough to offer this procedure to our patients.

Kayla Ford, RN, BSN, MSN-LA, can be contacted at Kayla.Ford@bannerhealth.com.

Recommended reading 

1. Engelhardt TC. Pulmonary embolism: the SEATTLE II trial. Cath Lab Digest 2013; 21(1): 1-20. Available online at https://www.cathlabdigest.com/articles/Pulmonary-Embolism-SEATTLE-II-Trial. Accessed May 22, 2013.